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Description

The SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product from the Surface Water Ocean Topography (SWOT) mission provides global sea surface height and significant wave height observations derived from low rate (LR) measurements from the Ka-band Radar Interferometer (KaRIn). SWOT launched on December 16, 2022 from Vandenberg Air Force Base in California into a 1-day repeat orbit for the "calibration" or "fast-sampling" phase of the mission, which completed in early July 2023. After the calibration phase, SWOT entered a 21-day repeat orbit in August 2023 to start the "science" phase of the mission, which is expected to continue through 2025. <br>
The L2 sea surface height data product is distributed in one netCDF-4 file per pass (half-orbit) covering the full KaRIn swath width, which spans 10-60km on each side of the nadir track. Sea surface height, sea surface height anomaly, wind speed, significant waveheight, and related parameters are provided on a geographically fixed, swath-aligned 2x2 km2 grid (Basic, Expert, Windwave). The sea surface height data are also provided on a finer 250x250 m2 "native" grid with minimal smoothing applied (Unsmoothed).<br>
Please note that this collection contains SWOT Version C science data products. <br>
This dataset is the parent collection to the following sub-collections: <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_Basic_2.0 <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_WindWave_2.0 <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_Expert_2.0 <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_Unsmoothed_2.0 <br>

Product Summary

Platforms
SWOT
Instruments
KaRIn ,
Jason-class Altimeter ,
AMR ,
DORIS ,
GPSP ,
LRA
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
2 Kilometers x 2 Kilometers<br>250 Meters x 250 Meters
Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2022-12-16
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2799438306-POCLOUD
Data State
SUPERSEDED
Number of Files/Granules
90959
Processing Level
2
Published
Updated
Science Keywords
Sea Surface Height ,
Significant Wave Height

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

SWOT. (2024). SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-SSH-2.0 Date Accessed: 2025-12-14

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Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
/left/ancillary_surface_classification_flag 7-state surface type classification computed from a mask built with MODIS and GlobCover data. N/A ubyte 255 0 to 6 1
/left/latitude Latitude of measurement [-80,80]. Positive latitude is North latitude, negative latitude is South latitude. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6
/left/latitude_uncert 1-sigma latitude uncertainty. degrees ushort 65535 0 to 20000 1.0E-6
/left/longitude Longitude of measurement. East longitude relative to Greenwich meridian. degrees_east int 2147483647 0 to 359999999 1.0E-6
/left/longitude_uncert 1-sigma longitude uncertainty. degrees ushort 65535 0 to 20000 1.0E-6
/left/mean_sea_surface_cnescls Mean sea surface height above the reference ellipsoid. The value is referenced to the mean tide system, i.e. includes the permanent tide (zero frequency). m int 2147483647 -1500000 to 1500000 0.0001
/left/miti_power_250m Center-beam 250 meter resolution power from KaRIn in real, linear units (not decibels). 1 float 9.96921E+36 -1 to 16777215 1
/left/miti_power_var_250m Center-beam 250 meter resolution power variance from KaRIn in real, linear units (not decibels). 1 float 9.96921E+36 -1 to 16777215 1
/left/polarization_karin H denotes co-polarized linear horizontal, V denotes co-polarized linear vertical. N/A string N/A N/A 1
/left/sig0_karin_2 Normalized radar cross section (sigma0) from KaRIn in real, linear units (not decibels). The value may be negative due to noise subtraction. The value is corrected for instrument calibration and atmospheric attenuation. A meteorological model provides the atmospheric attenuation (sig0_cor_atmos_model). 1 float 9.96921E+36 -1000 to 10000000 1
/left/sig0_karin_2_qual Quality flag for sigma0 from KaRIn in sig0_karin_2 variable. N/A uint 4294967295 0 to 3809426975 1
/left/sig0_karin_uncert 1-sigma uncertainty on sigma0 from KaRIn. 1 float 9.96921E+36 0 to 1000 1
/left/ssh_karin_2 Fully corrected sea surface height measured by KaRIn. The height is relative to the reference ellipsoid defined in the global attributes. This value is computed using model-based estimates for wet troposphere effects on the KaRIn measurement (e.g., model_wet_tropo_cor and sea_state_bias_cor_2). m int 2147483647 -15000000 to 150000000 0.0001
/left/ssh_karin_2_qual Quality flag for sea surface height from KaRIn in ssh_karin_2 variable. N/A uint 4294967295 0 to 3809459807 1
/left/ssh_karin_uncert 1-sigma uncertainty on the sea surface height from the KaRIn measurement. m ushort 65535 0 to 60000 0.0001
/left/time Time of measurement in seconds in the UTC time scale since 1 Jan 2000 00:00:00 UTC. [tai_utc_difference] is the difference between TAI and UTC reference time (seconds) for the first measurement of the data set. If a leap second occurs within the data set, the attribute leap_second is set to the UTC time at which the leap second occurs. seconds since 2000-01-01 00:00:00.0 double N/A N/A 1
/left/time_tai Time of measurement in seconds in the TAI time scale since 1 Jan 2000 00:00:00 TAI. This time scale contains no leap seconds. The difference (in seconds) with time in UTC is given by the attribute [time:tai_utc_difference]. seconds since 2000-01-01 00:00:00.0 double 9.9692099683869E+36 N/A 1
/left/total_coherence Total KaRIn interferometric coherence. 1 short 32767 0 to 10000 0.0001
/right/ancillary_surface_classification_flag 7-state surface type classification computed from a mask built with MODIS and GlobCover data. N/A ubyte 255 0 to 6 1
/right/latitude Latitude of measurement [-80,80]. Positive latitude is North latitude, negative latitude is South latitude. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6
/right/latitude_uncert 1-sigma latitude uncertainty. degrees ushort 65535 0 to 20000 1.0E-6
/right/longitude Longitude of measurement. East longitude relative to Greenwich meridian. degrees_east int 2147483647 0 to 359999999 1.0E-6
/right/longitude_uncert 1-sigma longitude uncertainty. degrees ushort 65535 0 to 20000 1.0E-6
/right/mean_sea_surface_cnescls Mean sea surface height above the reference ellipsoid. The value is referenced to the mean tide system, i.e. includes the permanent tide (zero frequency). m int 2147483647 -1500000 to 1500000 0.0001
/right/miti_power_250m Center-beam 250 meter resolution power from KaRIn in real, linear units (not decibels). 1 float 9.96921E+36 -1 to 16777215 1
/right/miti_power_var_250m Center-beam 250 meter resolution power variance from KaRIn in real, linear units (not decibels). 1 float 9.96921E+36 -1 to 16777215 1
/right/polarization_karin H denotes co-polarized linear horizontal, V denotes co-polarized linear vertical. N/A string N/A N/A 1
/right/sig0_karin_2 Normalized radar cross section (sigma0) from KaRIn in real, linear units (not decibels). The value may be negative due to noise subtraction. The value is corrected for instrument calibration and atmospheric attenuation. A meteorological model provides the atmospheric attenuation (sig0_cor_atmos_model). 1 float 9.96921E+36 -1000 to 10000000 1
/right/sig0_karin_2_qual Quality flag for sigma0 from KaRIn in sig0_karin_2 variable. N/A uint 4294967295 0 to 3809426975 1
/right/sig0_karin_uncert 1-sigma uncertainty on sigma0 from KaRIn. 1 float 9.96921E+36 0 to 1000 1
/right/ssh_karin_2 Fully corrected sea surface height measured by KaRIn. The height is relative to the reference ellipsoid defined in the global attributes. This value is computed using model-based estimates for wet troposphere effects on the KaRIn measurement (e.g., model_wet_tropo_cor and sea_state_bias_cor_2). m int 2147483647 -15000000 to 150000000 0.0001
/right/ssh_karin_2_qual Quality flag for sea surface height from KaRIn in ssh_karin_2 variable. N/A uint 4294967295 0 to 3809459807 1
/right/ssh_karin_uncert 1-sigma uncertainty on the sea surface height from the KaRIn measurement. m ushort 65535 0 to 60000 0.0001
/right/time Time of measurement in seconds in the UTC time scale since 1 Jan 2000 00:00:00 UTC. [tai_utc_difference] is the difference between TAI and UTC reference time (seconds) for the first measurement of the data set. If a leap second occurs within the data set, the attribute leap_second is set to the UTC time at which the leap second occurs. seconds since 2000-01-01 00:00:00.0 double N/A N/A 1
/right/time_tai Time of measurement in seconds in the TAI time scale since 1 Jan 2000 00:00:00 TAI. This time scale contains no leap seconds. The difference (in seconds) with time in UTC is given by the attribute [time:tai_utc_difference]. seconds since 2000-01-01 00:00:00.0 double 9.9692099683869E+36 N/A 1
/right/total_coherence Total KaRIn interferometric coherence. 1 short 32767 0 to 10000 0.0001
ancillary_surface_classification_flag 7-state surface type classification computed from a mask built with MODIS and GlobCover data. N/A ubyte 255 0 to 6 1
cross_track_angle Angle with respect to true north of the cross-track direction to the right of the spacecraft velocity vector. degrees int 2147483647 0 to 359999999 1.0E-6
cross_track_distance Distance of sample from nadir. Negative values indicate the left side of the swath, and positive values indicate the right side of the swath. m float 9.96921E+36 -75000 to 75000 1
dac Model estimate of the effect on sea surface topography due to high frequency air pressure and wind effects and the low-frequency height from inverted barometer effect (inv_bar_cor). This value is subtracted from the ssh_karin and ssh_karin_2 to compute ssha_karin and ssha_karin_2, respectively. Use only one of inv_bar_cor and dac. m short 32767 -12000 to 12000 0.0001
distance_to_coast Approximate distance to the nearest coast point along the Earth surface. m ushort 65535 0 to 21000 1000
doppler_centroid Doppler centroid (in hertz or cycles per second) estimated by KaRIn. 1/s short 32767 -30000 to 30000 1
dynamic_ice_flag Dynamic ice flag for the location of the KaRIn measurement. N/A ubyte 255 0 to 3 1
geoid Geoid height above the reference ellipsoid with a correction to refer the value to the mean tide system, i.e. includes the permanent tide (zero frequency). m int 2147483647 -1500000 to 1500000 0.0001
heading_to_coast Approximate compass heading (0-360 degrees with respect to true north) to the nearest coast point. degrees ushort 65535 0 to 35999 0.01
height_cor_xover Height correction from crossover calibration. To apply this correction the value of height_cor_xover should be added to the value of ssh_karin, ssh_karin_2, ssha_karin, and ssha_karin_2. m int 2147483647 -100000 to 100000 0.0001
height_cor_xover_qual Flag indicating the quality of the height correction from crossover calibration. Values of 0, 1, and 2 indicate that the correction is good, suspect, and bad, respectively. N/A ubyte 255 0 to 2 1
ice_conc Concentration of sea ice from model. % short 32767 0 to 10000 0.01
internal_tide_hret Coherent internal ocean tide. This value is subtracted from the ssh_karin and ssh_karin_2 to compute ssha_karin and ssha_karin_2, respectively. m short 32767 -2000 to 2000 0.0001
internal_tide_sol2 Coherent internal tide. This value is currently always defaulted. m short 32767 -2000 to 2000 0.0001
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